Here was my recommendation. I'd be interested in other peoples' comments.
It really stinks to be asked for your opinion and then have it ignored. I have sometimes seen that sort of dynamic set up when someone's manager tells them to ask for help, and they resent the order from their manager. (Frequently, they feel like it reflects on their own competence.) They can't disrespect their manager, so they disrespect the person whose advice they have been told to seek.If you're stuck in that sort of dynamic, make your written recommendations, cc your boss and their boss so that they know that the recommendations have been made in a businesslike and thoughtful way. (You may need to let the report sit overnight and re-edit it in the morning to remove any lingering snarkiness left over from your own hurt feelings from being disrespected.)
Then move on. You have fulfilled your request in a businesslike way. What they do with their time and their responsibility is on them.
In the case where you are asked to interview a bunch of subjects, give a written evaluation of them (I usually use a letter grade like in school--A, B+, D-, etc as a way to summarize), and leave the decision to them.
(If you look at the NFL scouting reports on players from before the draft, you will see a really useful approach to looking at the qualifications of a candidate in a summary way. You probably won't be talking about how fast the candidate runs the 40-yard dash, so substitute in professional requirements instead.)